Gauge for internal tapered threads



Dec. 23, 1952 J. RAOUT 2,622,336

. GAUGE FOR INTERNAL TAPERED THREADS Filed Oct. 25, 1948 2 2 SHEETS-SHEET 1 cl I Dec. 23, 1952 RAOUT 2,622,336

GAUGE FOR INTERNAL TAPERED THREADS Filed Oct. 25, 1948 2 SPEETS-SHEET 2 In 1170 r- T9104 44.007- ,5 M7 fflux Patented Dec. 23, 1952 UNI-TE D STATES OFF! CE? GAUGE FO-R INTERNAL TAPERED THREADS J can-Raout, Paris, .-Franc.e\ 1

Application Octber25, 1948, Serial No. 56,278

In 'France October 31, 1947 Claims'.

Thexapparatusthatforms. the objector my invention:is;.'intended1for one :or more of the I foi 1 lowing; purposes: 1 1

1. Me'asuringrof itheitaper:.-of tapered f-th'reads standingrzofz the "present description; the =accom= panyingdrawings illustrate in'" Figure 11,: an explanatory diagrammatic View."

Figure 2, a vie'w partly elevationaland partly cross-tsectional of a first method of execution "of the invention.

Figures 4 and ="5 are cross-sectional 'views'of design check gauges intended for setting the apparatus.

The apparatusus provi'dediwith" a spindle '2 (Figure, 2) :onwwhich is 'set,".at:ithe front part; a first feeler-disk I having a single-turn of 'eX- ternal tapered thread and 1 anrinternal threaded part to be screwed onto corresponding threads, on the spindle 2 to come into "contact withltheshonldertjli 'ongthe spindle. The shoulderrfi is.v engraved withfan adjustirigmarklfi, andia cor, respondin adjusting mark .I I "has ,been drawn onlthe -feeler-.disk I and 'this, mark I? has -to coincide with the mark I6 in order that the assembly of the feeler-disk --is'- accurately done.

The ,spindle 2 is next fitted with a slider 8 that :may either rotate 301" slide lengthwise on the said spindle, and may be fastened to it in any required position by tightening the screw I.

The slider carries, screwed on it, and tightened against the shoulder I8, a second feeler-disk 3 having a single turn of external tapered thread. On the slider 8, also, a micrometric barrel 5 is assembled and is intended to bear on the end face of the test piece of which the tapered screw thread is to be measured. This barrel 5 may be screwed or unscrewed, by means of the micrometric screw thread I9, on the slider 8. Its position is measured by the displacement of the fiducial line with regard to the graduated edge 20f: an-iadjustable" th mble w'fixed onyzthe slideri8; The startirigposition of this graduated thimble fi may :be 'set by :a previous adjusting operation; and fastened by tightening the screw 1 The tslidern-8i'carries, besides; :at its rear por:

tion anothergraduatedthimbIe 9 that 'iscapable of being zsecurediniit's starting position by means of a screw:.2 I; and in:front of-which moves-the fiducial" lines '22" of a:micrometric fbarrel ID that may be screwed or unscrewediin -relation--to the: spindle ."2 *by; means ofa =micrometric' screw thread :23;

The spindle 2 is provided with an operating knob l 2' secured thereto 'bymeans of a pin I I.-

In :ordentd measure" the characteristi'cs of a thread; :withthis appa-ratuazthe procedure is as:

follows:

(a) Setting up. The;:first; step-"is -an adjust-'5 ing pperationzby g-means 10f? check gauges- '24 and 25 (Figures-A and '5): corresponding'to the size:

of thread to be qmeasuredi Each gauge is pro-:- vided'-'.withithre'e sets ref-studs 25; the end surfaces of which-constitute ttwo reference gplanes including a standard length. These'zgauges' are placed inthe positionsshown in. dotted lines: in

Figure 2. The-barrels--5 and Iflarethenzbrought to: contact zand'cthe graduated thimbles.- .5 and-19 aresecuredr by means *ofitheirzscrews -I and :12 I

so that theinzeroscoincidewwithrthe fiducial: lines 20 1 and-12 .ofmthe barrels 5 2 and il I) (1)) (Measuringrv the tapers-The .-pitch diam.-.

eters A, and A of the, :two threadeddisk: I and. v

3 being known, the"calculation,.of;the.-:taper:ree

quires a measurement of rthezdistance between? them. This distance 11 (Figure-v11): ishequalto Z3 plus-a known vconstant;value-and .mayibe measured 'consequentlyyby :means; of 5 the eabarrel I I0 1 (Figure-2) ,the readingqbeing made on the scale 9.

T0 1 carry out the measurement; first i the 1 threaded disks I3Iand-3 arescrewedtintturn into the threaded part being i-examined: The barrel- I0 .is: next brought to contact withlthe rear face of the slider. :8. Then 1 the .readingymaderon: the

scale of the graduated thimble 9, gives the departure from normal in the distance of the two disks, enabling any error in taper to be computed.

(0) Measuring the pitch-diameter at gauge point.-This datum is in relation to the distance Z2 (Figure 1) at which the rear feeler lies from the rear face of the test piece and this distance Z2 is equal to L1 plus a known fixed value. A numerical table will enable the diameter sought for to be more easily evaluated when 14 has been measured.

In order to make this measurement, the

3 threaded disk 3 is first screwed into the thread under test, then the barrel is screwed until it comes to contact with the rear face of the threaded part. The distance Z4 is then read on the scale 6.

((2) Indirect measurement of the pitch-After the instrument has been withdrawn from the threaded part, the two feelers are set up again in the position they were occupying when both were screwed in the threaded part, i. e. in the position recorded by the reading 13, previously made for taper measurement.

This leads up to the measurement of the pitch of a male taper thread, that may be easily carried out by means of any suitable auxiliary apparatus.

The modified apparatus illustrated in Figure 3 is so designed as to simplify for the reading of the taper the indirect measurement of the pitch. The two feeler-disks and the slider are set up as in the case of Figure 2, but rear thimble 21 is not graduated. It only carries a mark 28. The barrel 3!), similar to H1 in Figure 2 is adapted to be brought to contact by micrometric motion, with the rear face of the slider 8. It carries also an indicia line 29 and on its rear portion, a fiducial line 33 working in conjunction with an adjustable graduated thimble 32, against which readings are made.

Under such conditions, the indirect measurement of the pitch takes place in the following way:

At the stage of the taper measurement carried out as stated above by reading the dimension la, the mark 28 is brought opposite to the mark 29 and the thimble 21 is fixed on the slider in this position by means of the screw 34.

In order to set up again the comparative position of the feeler-disks, after withdrawing them from the threaded part, all that has to be done is to reproduce the reading 13 and to bring again the adjusting marks 28 and 29 exactly opposite to each other.

The accuracy of the apparatus according to the invention is of a very high degree.

For a 25% taper, a variation of one division on the graduated thimble 32 (Figure 3) implies a variation of 2.5 microns in the taper.

For the barrel 5 in conjunction with the thimble 6, a variation of one division (corresponding to microns) involves on the same taper-a variation of 2.5 microns on the value found for the diameter.

What I claim is:

1. An apparatus for measuring the characteristics of internal tapered threads comprising in combination a spindle, a first feeler mounted in adjusted position upon said spindle, a slider freely displaceable upon said spindle, a second feeler mounted in adjusted position upon said slider, a barrel having a front face, a rear reference face on said slider, said front face adapted to abut said rear reference face on said slider, said barrel being adjustably mounted upon said spindle and a graduated thimble adjusted during initial setting and against which the position of said adjustable barrel is read, in order to measure the taper.

2. An apparatus as set forth in claim 1 in which said feelers are disks and wherein the rear face of the first feeler and the front face of the second feeler are so designed as to permit an initial setting by means of a gauge.

3. An apparatus as set forth in claim 2 in which said feelers are demountable and comprise a single turn of a conveniently shaped thread.

4. An apparatus for measuring the characteristics of a tapered thread comprising in combination a spindle, a first feeler mounted in adjusted position upon said spindle, a slider freely movable upon said spindle and having a rear reference face thereon, a second feeler mounted in adjusted position upon said slider, a micrometric barrel mounted upon said slider and having a flat front face, designed to come to rest on the end face of a test piece upon said slider, a graduated adjustable thimble on said slider, the positions of said barrel being read against said graduated adjustable thimble, another micrometric barrel mounted adjustably upon said spindle and having a front face which can come to rest against the rear face of said slider, and a graduated thimble fixed during initial setting upon said spindle and against which are read the displacements of said adjustable barrel in order to measure the taper.

5. An apparatus for measuring the characteristics of internal tapered threads comprising in combination a spindle, a threaded primary feeler assembled in set position on said spindle, a slider that maybe shifted likewise assembled on said spindle, a second threaded feeler assembled in set position on said slider, a micrometric barrel and a graduated thimble adjustably mounted on said slider cooperating with said second feeler, a second micrometric barrel movably mounted on said spindle, and micrometric measuring means cooperating with said second barrel.

JEAN RAOUT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date 

